1. Field of the Invention
This invention relates to a discharge gap device and a power supply device which are adapted to discharge a lightning surge or static electricity.
2. Description of the Related Art
FIG. 7 is a top view of a discharge gap device according to the related art. In FIG. 7, the arrow F denotes a predetermined gap (which will be called gap F) between the end 201A of a first discharge pattern 201 and the end 202A of a second discharge pattern 202. The gap F is a predetermined interval which is appropriate for discharging a lightning surge or static electricity.
As illustrated in FIG. 7, the discharge gap device 200 according to the related art is a discharge gap pattern for discharging a lightning surge or static electricity, and this discharge gap device 200 includes a first discharge pattern 201 and a second discharge pattern 202.
The first discharge pattern 201 is formed integrally with a first wiring pattern 204. The first discharge pattern 201 includes a pointed edge (which includes a triangular cross-section) and projects from the first wiring pattern 204. The first discharge pattern 201 includes a thickness which is the same as a thickness of the first wiring pattern 204.
The second discharge pattern 202 is formed integrally with a second wiring pattern 205. The second discharge pattern 202 includes a pointed edge (which includes a triangular cross-section), and projects from the second wiring pattern 205. The second discharge pattern 202 includes a thickness which is the same as a thickness of the second wiring pattern 205.
The first and second discharge patterns 201, 202 are arranged so that the end 201A of the first discharge pattern 201 and the end 202A of the second discharge pattern 202 face each other and the gap F between the end 201A and the end 202A is defined.
The above-described discharge gap device 200 is provided for use in a power supply device (refer to FIG. 8).
FIG. 8 is a diagram illustrating the composition of a power supply device including the discharge gap device according to the related art. In FIG. 8, the elements which are the same as corresponding elements illustrated in FIG. 7 are designated by the same reference numerals, and a description thereof will be omitted. For the sake of convenience, a line filter 212 is illustrated by the one-dot chain line in FIG. 8.
As illustrated in FIG. 8, the power supply device 210 includes a substrate 211, two first wiring patterns 204, two second wiring patterns 205, two discharge gap devices 200, a line filter 212, a power supply 213, and an internal circuit 215.
The first and second wiring patterns 204,205 and the discharge gap device 200 are disposed on substrate 211. Each first wiring pattern 204 includes a terminal part 204A to which the terminal of the line filter 212 is connected. Each first wiring pattern 204 is electrically connected to the line filter 212 and the power supply 213.
Each second wiring pattern 205 includes a terminal part 205A to which the terminal of the line filter 212 is connected. Each second wiring pattern 205 is electrically connected to the line filter 212 and the internal circuit 215.
The first and second wiring patterns 204,205 are arranged so that one end of the first wiring pattern 204 confronts one end of the second wiring pattern 205. Each discharge gap device 200 is disposed in the first and second wiring patterns 204,205 where the end of the first wiring pattern 204 confronts the end of the second wiring pattern 205.
The line filter 212 is provided for eliminating noises, and this line filter 212 includes four terminals. The line filter 212 is mounted on the terminal parts 204A and 205A of the first and second wiring patterns 204,205.
The power supply device 210 causes the discharge gap device 200 to discharge a lightning surge or static electricity induced by the energy accumulated in the line filter 212, in order to prevent the breakage of the internal circuit 215. Refer to Japanese Laid-Open Patent Publication No. 2002-232091.
FIG. 9 is a diagram for explaining the problem of the discharge gap device according to the related art. In FIG. 9, the elements which are the same as corresponding elements in FIG. 7 are designated by the same reference numerals, and a description thereof will be omitted.
In the discharge gap device 200 according to the related art, each of the first and second discharge patterns 201,202 includes a pointed edge, and when a repeated discharge operation is performed, the pointed edges of the first and second discharge patterns 201,202 are damaged as illustrated in FIG. 9.
As a result, the gap between the first discharge pattern 201 and the second discharge pattern 202 is enlarged so that it is larger than the predetermined gap F. In such a case, it is impossible for the discharge gap device 200 to discharge the energy resulting from a lightning surge or static electricity.